Contribution a l'etude de la transformation thermique des aldazines α-ethyleniques. nouvelle voie d'acces aux pyrazoles halogenes ou substitues par des groupements phenoxy, thiophenoxy et thioethoxy en 3(5)
作者:P. Freche、A. Gorgues、E. Levas
DOI:10.1016/0040-4020(77)80315-3
日期:——
Azines of β-halogen-, aryloxy-, alkylthio- and arylthio-substituted acroleines when heated gave pyrazole derivatives which may be hydrolysed very easily to give N-unsubstituted pyrazoles bearing in the 3(5) position halogen, ArO, RS or ArS groups. The observed heterocyclisation was compared with thermal decomposition of cinnamald azine for which an ionic mechanism had been previously proposed, whereas
β-卤素,芳氧基,烷硫基和芳硫基取代的丙烯醛在加热时会生成吡唑衍生物,吡唑衍生物很容易被水解,从而生成在3(5)位卤素,ArO,RS或ArS基团的N-未取代的吡唑。将观察到的杂环化与肉桂醛的热分解进行了比较,肉桂醛的热分解先前已提出了离子机制,而我们证明所涉及的机制是内部的1,4-加成,并且根据迁移基团的性质,热分解[ 1,3]或[1,5]σ重排。